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[MMUSIC] Question about RTSP proxy
Hi all,
In RTSP 2.0, it is permitted to
transmit several client requests in one Transport Connection.
I think this may introduce new
problems when RTSP proxy is intervened, and existing RTSP can not deal with
the scenario correctly.
The following is an example. To
display the figure correctly, please maximize this email
window.
Suppose that
client A and client B wants to join different multicast groups on the same
server.
+----------+
+--------------+
+--------+
| Client A
|
| RTSP proxy|
| Server |
+----------+
+--------------+
+--------+
|
|
|
|
+----------+
|
|
|
| Client B
|
|
|
|
+----------+ |
|
|
|
|
|
| |
Setup
|
|
|==================>
|
|
|
|
|
|
|
|
|
Setup
|
|
|
|====================> |
|
|
|
|
| |
Setup
|
|
|
|*****************>|
|
|
| |
Setup
|
|
|
|************************>
|
|
|
|
|
|
|
|
|
|
|
|<=====================|
|
|
| 200 OK
(SessionID=12345678)|
|
|
|<************************
|
|
|
| 200 OK (SessionID=23456789)|
|
|
?????????|
|
|
|
|
|
Fig.2
Multicast
The interactive
messages are listed as following.
Session issued by
Client A:
C->P: SETUP rtsp://live.example.com/concert/audio
RTSP/2.0
CSeq:
111
Transport:
RTP/AVP;multicast
P->S: SETUP
rtsp://live.example.com/concert/audio
RTSP/2.0
CSeq:
333
Transport:
RTP/AVP;multicast
Session issued by
Client A:
C->P: SETUP
rtsp://live.example.com/anotherconcert/audio
RTSP/2.0
CSeq:
222
Transport:
RTP/AVP;multicast
P->S: SETUP
rtsp://live.example.com/anotherconcert/audio
RTSP/2.0
CSeq:
444
Transport:
RTP/AVP;multicast
Proxy will receive the following responses
from server:
S->P: RTSP/2.0 200
OK
CSeq:
333
Server:
PhonyServer/1.0
Date: Thu,
23 Jan 2009 15:35:06 GMT
Transport:
RTP/AVP;multicast;
dest_addr="224.2.0.1:3456"/"224.2.0.1:3457";ttl=16
Session: 12345678
S->P: RTSP/2.0 200
OK
CSeq:
444
Server:
PhonyServer/1.0
Date: Thu,
23 Jan 2009 15:35:06 GMT
Transport:
RTP/AVP;multicast;
dest_addr="224.2.0.2:1234"/"224.2.0.2:1235";ttl=16
Session: 23456789
In this case, RTSP proxy
can not distinguish the responses, then it may respond client with wrong
message and induce client to join a wrong mutlicast group.
Do anybody think this is an
possible trap/deficiency, and RTSP should try to
resolve?
Thanks.